Thursday, December 8, 2011

An antenna in your clothes for more reliable communications

AppId is over the quotaAppId is over the quota Summary: Ohio State University researchers report a new wearable antenna design with a range four times larger than that of a conventional antenna, such as those worn by American soldiers today.

The modern soldier routinely carries between 60 and 100 pounds of gear, so anything that can improve conditions can go a long way. Engineers at Ohio State University are chipping away at part of the problem by finding ways to incorporate radio antennas directly into clothing using plastic film, metallic thread, and a household sewing machine.

The Ohio State team has developed a new prototype antenna with a range four times larger than that of a conventional antenna worn on the body. It can send and receive signals in all directions, even through walls and inside a building, without a need for the wearer to carry an external antenna.

Credit: Ohio State University

“Our primary goal is to improve communications reliability and the mobility of the soldiers,” said Chi-Chih Chen, a research associate professor of electrical and computer engineering at Ohio State. “But the same technology could work for police officers, fire fighters, astronauts – anybody who needs to keep their hands free for important work.”

As anyone with an early iPhone 4 can attest to, when antennas make contact with the human skin, the body tends to absorb radio signals and form a short circuit. And if an antenna is improperly placed, a person’s body can block the signal when moving against a wall or other obstacles.

To overcome these obstacles, the engineers used several antennas surrounding the body which work in concert to transmit or receive a signal, no matter which way a person is facing. A compact integrated computer senses body movement and switches between the antennas to activate the one with the best performance given the body’s position.

The UHF body-worn antenna was made from thin layers of brass etched on a commercially available plastic film, called FR-4. The film is light and flexible, and can be sewn onto fabric. The antenna was then attached into a vest at four locations –chest, back, and both shoulders. The computer controller–a metal box a little smaller than a credit card and an inch thick–was attached to a belt.

In laboratory tests, the antenna system provided significantly greater signal strength compared to a conventional military “whip” antenna, report the researchers, enabling a range of communications four times larger.

The next step for the Ohio State engineers is to partner with an antenna design company, Applied EM of Hampton, VA, to commercialize the research, which was funded by a Small Business Innovation Research grant. Chen estimates that the prototype antenna system would cost $200 per person to implement, but mass production would bring that cost significantly down.

in addition to soldiers and law enforcement personnel, the OSU researchers envision the technology adapted for the general public, such as the elderly or disabled who could wear clothing that would let them communicate in case of emergency.

A paper covering the new antenna design is published in the current issue of the journal IEEE Antennas and Wireless Propagation Letters.